System of control



March 16 1926 R. w. M NElLL SYSTEM OF CONTROL Filed Jan. 8,, 192 1 WITNESSES:

INVENTOR 1 Ralph Wfic/Vf/Z "ATTORNEY Patented Mar. 16, 1926.

UNITED STATES Parent crates.

RALPH W. MGNEILL, OF EDGEWOOD, IENNSYLVAK'IA. ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MAN'UFACT URING COMPANY, A CORPORATION OF PENNSYLVANIA.

sxs'rnm or counter.

"Application filed January 8, 1921. Serial No. 435,787.

To all whom it may concern Be, it known that I, RALrH V. McN mm, a citizen of the United States, and a resident of Edgewood, in the county of Allegheny and State of Pennsylvania, have invented a new'and useful Improvement in Systems of Control, of which the following is a specification.

My invention relates to motor-control systems and particularly to such systems as are employed with elevators, hoists and similar mechanisms.

The object of my invention is to provide means for controlling the speed of a hoisting motor and to provide automatic means for insuring graduated deceleration, or

slow-down of the motor at either limit of travel of the car, prior to stopping.

It is proposed to provide a standard hoisting system with a switching mechanism operated by a centrifugal governor controlled in accordance .with the speed of the hoisting drum. This switching mechanism is also controlled by a travelling-nut'mec-hanism or a. rotatable cam so geared to the hoisting drum that the cam will make approximately one revolution during the total travel of the car or for a predetermined number of rota-y ,tions of the hoisting drum.

This switching mechanism controls the power supplied to the motor and will be actuated by the governor to produce a normal operating speed of the hoisting drum should the latter for any reason, exceed a predetermined operating speed. Also, in order to accomplish reasonable stops upon ap proaching the limits of travel, graduated deceleration, or slow-down, will be simi-. larly accomplished by the actuation of the rotatable cam.

My invention will be described in conneo tion'with the uccompanying drawings in which Figure 1 is a diagrammatic view of cir-' cuits and apparatus embodylng my 1nven-- tion.

Fig. 2 is a diagrammatic view of the hoisting mechanism.

Referring particularly to Fig. 1, alstand ard reversing control system is employed in connection with an electric motor. Any suitable control system may be employed. The system is also applicable to a steam hoist wherein the switching mechanism may con ol the s eam throttle. However, in the accompanying drawing, the switching mechanism is shown, for simplicity, as contr lling main line or reversing switches.

Referring to Fig. 2, a hoisting drum 1 and a governor 2 are connected through gearing.

and the governor is actuated in accordance member 4 is pivotallyconnected to rod 3 and normally moves, and is in engagement, with contact member 5. It is also capable of independent movement. A lever 6, which is pivota-lly connected to rod 3, is provided with a roller 7 that rides on a cam 8 which is rotated by the hoisting drum 1.

In Figure 1, a motor armature 9, which is controlled by a master switch 10, is connected, by reversing co-ntactors 11 and 12, to line conductors 13 and 14. An accelerating resistor 15 is controlled by a contactor 16. The motor field-magnet winding 17 is connected in shunt relation to the armature 9.

In normal operation, the master switch 10 is actuated to the left to establish acircuit for the up direction of travel which may be traced from the positive line conductor 13, through conductor 18, conductor 19, governor switch contact members 4 and 5, master switch contact members 20, 21 and 22, conductor 23 and coil 24, to the negative line conductor 14. Contactor 12 is actuated to establish a main motor circuit extending from the positive line conductor 13, though conductor'18, contactor 12, conductor 25, armature 9, conductor 26, cont-actor 12, conductor 27, accelerating resistor 15 and conductor 28, to the negative line conductor 14. An accelerating contactor 16, with its coil 31 connected across the armature terminals, is actuated in a well-known manner,.in accordance with the counter electromotive force of the armatiire, to shunt the accelerating resistor 15 at a predetermined motor speed. A circuit for the motor field-magnet winding 17 extends from the positive line conductor 13, through. conductors 18, 19 and 3a, field-magnet winding 17 and conductor 28 to the negative line conductor 14.

It 'may be assumed that the motor is now operating at normal speed, and contact mem- The overnor is rohers 4 and 5 float with the movement of rod 3, in accordance with the motor speed. If, for any reason, a predetermined or dangerous speed is attained. the rod 3 is lowered, causing lever 6 to tilt a sufiicient amount to lift co'ntact member 4 out of engagement with contact member 5. The circuit of actuating coil 24 of contactor 12 is broken and the latter opens the circuit of the motor. Upon the restoration of normal Speed, the power circuit is automatically restored by the engagement of contact members 4 and 5.

Cam 8 rotates somewhat less than 360 for a total travel of the hoist. Approaching either limit of travel, the roller 7 rises on an inclined portion of the cam to disengage con-. tact members 4 and 5'. Power is cut off and the motor speed is reduced, the governor speed is correspondingly reduced and rod 3 is. raised until lever 6 is sufficiently near to level position to restore contact members 4 and 5, when power is again applied momentarily, if the end of travel has not been reached. Finally, when the desired point of travel is attained, power is cut off by other means, such as hatchway limit switches of known character. In this system, thehoist never falls short of the desired level, since, power is intermittently applied as long as required. Nor. can the hoist exceed the proper level, since, upon approaching the limit at high speed, the governor rod 3 has an initial low position. Consequently, the cam dis'engages contact members 4 and 5 earlier than is the case when the speed is normal, power is cut off earlier and remains off until the speed is properly reduced. Power is again applied only if necessary to drive the hoist to the desired level.

-Actuating the master switch 10 to the right establishes a circuit to close contactor 11 and thereby reverse the rotation. of the motor, in a well-known manner, afteii' which the operation of the system is as previously described. T

If it is desired to operate the hoist more 'Sl0Wly than the normal rate or to decelera'te at a rate lower than normal, such 0 eration 1 may be accomplished by intermittent y opeuing and closing the motor circuit by means of the master switch. The automatic governor mechanism does not interfere with such operation so long as the speed is within' the predetermined limit and the hoist is bereciprocating device, a swltch and speed-re-- sponsive means for controlling said switch -.to limit the rate of movement of said device,

tween'the terminal limits.

It is evident that I have disclosed means for controlling the speed of a hoistin or similar mechanism in which the-contro ling means is [reduced to the simplest practical .form, combining the speed-governing elements with means for limiting the car travel. This system is particularly advantageous in that accurate terminal stops are accomplished independently of varying load or speed conditions. n

I claim as my invention 1. The combination witha motor-operated reciprocating device and speed-governed means for limiting the rate of operation thereof, of means comprising said limiting means for restricting the operation of the device to a predetermined range of movement.

2. The combination with a motor operated reciprocating device and a centrifugallyfoperated switch for controlling the motor circuit, of means, comprising said switch, for limiting the speed of the motor to insure a predetermined operating movement of said device.

3. The combination with a motor and a switch for controlling the motor circuit, of a centrifugal governor operatively connected to said motor for actuating said switch, and

i of said drum.

5. The combination with a hoisting drum and means for operating the drum, of aswitchactuated in accordance with the speed of said drum to control said operating means,

and a rotatable cam o eratively connected to said drum for actuating said switch within predetermined hoisting limits.

6. The combination with an electric motor and a switch .for controlling the motor of a hoisting drum operatively connected to said motor, a centrifugal governor operatively connected to the drum for actuating the switch and a rotatable cam operatively connected to said drum for actuatin said switch in accordance with the position of said governor to maintain in effect a power supply for said motor during deceleration.

7 The combination with a motor-operated reciprocating device and a speed responsive switch for limiting the rate of operation thereof, of means for automatically actuating said switch to limit-the range of movement of said device.

8. The combination with a motor-operated of means co-operating with said speed-responsive means to automatically actuate said switch to insure a predetermined range of operating movement of said device.

1920. RALPH W. MQNEILL. 

